1. Field of Invention
The present invention is directed towards a rotary die cut stacking system having an optical beam generator to assist with the positioning of layboy arms relative to a die cutter and to a method of mounting an optical beam generator in a rotary die cut stacking system, and, more specifically, towards a rotary die cut stacking system having a plurality of lasers mounted on layboy arms for assisting with the positioning of the layboy arms relative to a rotary die and to a method of mounting lasers on the layboy arms of a rotary die cut stacking system.
2. Description of Related Art
Devices for stacking sheets of material received from a rotary die cutter are well known. One example of such a device is the AGS2000 Rotary Die Cut Stacker made by the assignee of the present invention, A.G. Stacker, Inc., Weyers Cave, Va. Further examples of such devices are disclosed in U.S. Pat. Nos. 3,321,202 to Martin and 3,419,266 to Martin, each of which is expressly incorporated by reference in its entirety.
FIGS. 1 and 2 illustrate a conventional rotary die cut stacking system. As illustrated therein, the system 100 typically comprises a layboy section 102 which receives blanks or sheets of material, such as those produced by a rotary die cutting machine having a top die 126 and a bottom drum 128, and discharges the blanks onto a transfer conveyor 104. The transfer conveyor 104 receives the blanks and transports them to a main conveyor 106. The main conveyor 106 has an intake end 108 and a discharge end 110. At its intake end 108, the main conveyor 106 is mounted to a base 112 at a pivot point 114 so that the conveyor may be pivoted to raise the discharge end 110 of the conveyor 106. At the discharge end 110 of the conveyor 106, the blanks pass through an accumulator section 116 and form a stack at a stacking location 121.
The layboy section 102 has a first plurality of upper arms 130 and a second plurality of lower arms 132 which may be, but are not necessarily, equal in number. Typically, six to eight upper arms and six to eight lower arms are provided. Each of the upper and lower arms 130 and 132 is a moveable assembly rotatably supporting a driven belt 134. The belts 134 on the upper and lower arms 130 and 132 form a nip region 136 where sheets or blanks from the rotary die cutter are drawn into the layboy section 102.
Conventional die cutting machines may output one, two, three of four rows of blanks simultaneously. As these rows of sheets enter the nip region 136 in rows of one, two, three or four and move along the layboy section 102, the upper and lower arms 130, 132 steer the blanks and change the orientation and/or row spacing of the blanks in a predetermined manner so that the blanks are deposited onto the transfer conveyor 104 in a desired manner. When the layboy arms are used to space multiple rows of blanks, they will often not be parallel to each other, and they will not all be perpendicular to the surface of the die 126.
In conventional systems, an operator sets the positions of the layboy arms while standing on one side of the layboy section. Generally, a long rod is used to pull or push the individual arms back and forth in the width direction of the stacking machine to put the arms into appropriate positions. The layboy arms should be positioned so that they are not located between adjacent blanks and so that they contact parts of the blanks that can be readily driven. For example, on blanks having a plurality of openings or having flaps, it may be desirable for the bands of the layboy arms to contact the blanks at positions away from the flaps or openings. However, layboy 102 may be 80 to 200 inches wide, and the arms may each be angled differently with respect to the surface of the rotary die 126. The distance from the edge of the layboy 102 to a given arm 130, 132 and the angle that a particular arm makes relative to the die 126 make it difficult to determine whether the layboy arms 130, 132 are positioned appropriately. Therefore, several adjustments may be necessary when a new run of blanks is started to determine the proper position of each of the six to eight layboy arms. Shutting down a production line while such adjustments are made reduces efficiency and can be costly. Because the relative positions of the arms and the die may not be readily determined, it may be necessary to stop the die cutter and reposition the layboy arms several times before a satisfactory placement is obtained. Accordingly, it would be desirable to provide an apparatus and method for helping a machine operator to place the arms of a layboy in a desired position relative to a die cutter in an efficient manner.